Handpiece for rotary tools, especially for dentists&#39; use



Jan. 19, 1954 O. THA*JENSEN HANDPIECE FOR ROTARY TOOLS, ESPECIALLY FOR DENTISTS USE Filed 001,. 9, 1950 l INVENTOR. Orla Thau- Jensen BY (gd: @mAh-MMM ATT-qs,

Patented `fan. 19, 1954 OFFICE HANDPIECE FOR ROTARY TOOLS, ESPE- CIALLY FOR DENTISTS USE Orla Thau-Jensen, Hurup, Thy, Denmark Application October 9, 1950, Serial No. 189,124

4 Claims.

This invention relates to handpieces fork rotary tools, especially for dentists use.V lSuch handpieces comprise a preferably tubular casing having a tool chuck-carrying spindle mounted for rotation therein and ordinarily adapted to be connected to a flexible shaft.

One object of the invention is to provide a relatively simple and sturdy construction of such hanopieces requiring a minimum of attendance and affording a maximum of reliability in operation.

Another object is to provide a construction in which the rotary tools may be inserted and removed without stopping the rotation of the spindle oi the handpiece.

A further object is to provide a handpiece having a forward spindle bearing arranged close to the tool gripped in the tool chuck so as to insure a good radial support of such tool.

The invention is illustrated in the drawing in which:

Fig. 1 is an axial sectional View of a handpiece for rotary tools in accordance with this invention,

Fig. 2 is a similar view of another handpiece embodying the invention, and

Fig. 3 shows a modincation of the construction shown in Fig. 2.

Throughout the drawings like reference characters designate corresponding parts.

Referring now to Fig. 1, I denotes a tubular casing which is adapted to have its rear end connected to aflexible driving shaft in a manner which constitutes no part of the present invention. A spindle 2 adapted to be driven by such flexible shaft, is mounted in ball bearings 3 and 4 in the casing I, the spindle having a shoulder abutting against the inner ball race of the bearing Il, which latter is of a construction enabling it to withstand axial as well as radial thrust.

The forward enlarged end '22 of the spindle 2 is formed with an axial bore or recess 6 which, at its forward end is enlarged as indicated at 5. The inner end of the bore recess 6 is formed to constitute a conical seat l co-axial with the spindle 2. A slotted tool-gripping sleeve or chuck 8 is arranged in the bore 6 and is formed with conical end faces. The forward end of the chuck 8 is surrounded by a chuck-actuating socket 9 arranged in the enlarged portion `ii of the recess and having a conical seat I for the forward conical end of the chuck 8. .The socket 9 is provided with radial projections I2 engaging longitudinal slots I3 in the walls surrounding the recess 5, so that the socket is caused to rotate with the spindle 2, but is capable of axial displacement relative thereto. The forward end of the socket 9 is mounted in a ball bearing II and has a shoulder abutting against the inner ball race thereof. The ball bearing Il, which is also of a type capable of receiving axial thrust, has its outer race arranged in a cap I4 constituting the foremost portion of the casing I and connected to the latter by means of screw threads I5.

It will be appreciated that, when the cap Is is turned relative to the Vcasing I to screw it into the latter, the tool-gripping chuck 8 will be clamped between the conical seats 'i and Ill so as to be compressed around a shank I@ of a rotary tool I 'i introduced into the chuck. When the cap I4 is turned in the opposite direction, the tool-gripping chuck 8 is released, so that the tool I'I can be removed. It will be evident that this can be effected, irrespective of the fact, whether the spindle 2 is rotating, or not.

The handpiece described with reference to Fig. 1 is extremely easy to disassemble for cleaning by simply removing the screw cap M. The handpiece comprises a very small number of parts, as compared with the handpieces of the kind in question known heretofore, and presents no projecting levers or like parts which might hamper the handling of the device. An adjustment of the ball bearings of the handpiece is not required, any slackness thereof being taken up when the tool II is gripped in the chuck 8.

In the construction shown in Fig. 2, the casing I is provided with only one ball bearing 3 for the spindle 2, and the recessed forward end of the spindle is composed by two parts 23 and 24 connected together by means of screw threads so as to present a common axial bore 5 which is restricted at its forward end to constitute an inner conical seat Sli adapted to receive the for- Ward end of the tool-gripping chuck 8. A chuckactuating member 25 is arranged in the recess 6 behind the chuck 8 and is formed with a conical seat 35 engaging the rear end of the chuck S under the action of a helical spring IB interposed between the member 25 and the bottom of the recess 6. The member 25 is formed with radial projections or pins I2 extending through longitudinal slots I3 in the walls of the member 24. The forward end 23, 24 of the spindle is surrounded by a socket 26 constituting a sliding t therewith and having its forward restricted end mounted in the ball bearing I I in the screw cap I. The socket 2S is at its rear end formed with longitudinal slots 2 engaged by the pins r2, so that, when the cap ifi is screwed backwards relative to the casing I, the inner ends oi the slots 2i will engage the pins i2 to urge the chuck-actuating member 25 back against the action of the spring I8 t0 permit the toolgripping chuck 8 to expand so as to be capable of receiving the shank l5 oi the tool I'I. When subsequently the cap IZi is turned in 'a manner to move the bearing II forwards relative to the casing I, the spring I8 will urge the member 25 forwards to engage the chuck Yso that the latter is'compressed around the tool shank TE.

Obviously, with this construction the necessary force for compressing the tool-'gripping 'chuckis only delivered by the spring I=8 andis 'completely taken up within the spindle head 23, 24 so that no axial thrust is exerted upon the bearings 3 and il due to compress-ion of the tool-gripping chuck, i. e. these 'bearings are during operation only subjected to such axial thrust ras may 'be exerted by the tool II 'engaging .a workpiece. Only when the spring I3 is compressed by screwing back the cap 'M for exchanging Aor the tool I1, i. e. when the bearings '3 and v'II are subjected to no load due to the working of the tool I1, these bearings are subjected `to lan axial thrust equal to the compressive force `of 'the spring 128. The bearings are thus greatly relieved, as compared with the construction shown in Fig. 1 and'may, therefore, have correspondingly .smaller dimensions so as to make the handpiece more slender and handy.

The advanced position of the bearing ri I vin the constructions shown in Figures 1 and 2 makes the nose of the handpiece rather stumpy. This sturdy construction makes the .handpiece especially fit for dentists shopwork, i. e. boring, grinding etc. not effected on the patient, 'while handpieces intended. for clinical use 'should have a nose substantially inthe shape of a long and slender cone, so as to afford good views towards the place of operation. This involves v'a cer-tain retraction of the bearing I I, and -the modification illustrated in Fig. 3 shows, how this bearing can be arranged in a retracted position without fthe tool-gripping chuck 8 and the parts co-operating therewith being correspondingly retracted.

In the modication shown in Fig. `3 the head of the spindle 2 is composed by three parts '218, 29, 3B connected with each other by means of screw threads. The member 29 fis at its iol-ward end formed with a neck I9 which is Islidably guided in the bearing II and onto which the member 30 is threaded. The latter is restricted at its 'forward end to constitute an inner conical seat 36 and contains the slotted sleeve `8 "as well as a chuck-actuating member 3l having alconical seat 31. The member 3l is formed with an axial rearward extension 20 extending through the neck I9 and connected at its rear `end with a piston-like member '2l mounted 'for yaxial sliding movement in the spindle head 28 and subjected to the action of the coil spring t8. VThemember 2l carries the .radial pins i2 by Ameans 4of which connection is established between 'the member 3| and a socket 32.

The socket 32 is slidably guided upon the spindle hea-d 2% and engaged `with -i-ts Vforward restricted end at one side face of `the inner ball race of the bearing II. The principle of operation is the same as that ofthe construction shown in Fig. 2. It `will be appreciated that, in both instances'the bearings 3 and II are only subjected to axial thrust when the cap I4 is screwed back to compress the spring I8 and thereby to release the tool-shank I6 gripped in the sleeve 8, while during normal use of the handpiece the bearings will only have to take up the stresses imposed thereupon by the tool I1.

By removing the cap I4 and separating the parts 23, 24 or 28-30, respectively, of the spindle head, the whole hand piece can be disassembled for cleaning or repair.

I claim:

1. A handpiece for rotary tools, comprising a tubular casing, a spindle mounted for rotation therein by means of bearings adapted to receive axial and radial thrust, a recess in the forward end'oi Vsaid spindle co-axial therewith, a co-axial conical seat in said recess, a chuck-actuating member mounted for axial displacement relative to vsaid spindle and said casing and having another co-axial conical seat facing said firstname'd seat, `a tool-gripping chuck mounted b'etween said conical `seats Y.to be actuated thereby for gripping and releasing, respectively of Va toolshank, a cap at the .forward end of said casing and surrounding said kforward 'end of 'said spindle, said cap being adapted `to be .screwed .forwards and backwards relative Vto said casing and being operatively connected with `,said axially displaceable chuckactuating member for controlling axial Adisplacement thereof in accordance with axial displacement of said cap.

-2. A 'handpiece for rotary tools, comprising a tubular casing, va spindle mounted for rotation therein by means or bearings adapted -to receive axial and radial thrust, a recess in the forward end of said spindle `co-axial therewith, a co-'axial conical seat in said recess, a `c`l 1uck-actuating member mounted for axial displacement r'relative to said casing and said spindle vand having another co-axial conical seat vfacing 'said .ii-rstnamed seat, a tool-gripping chuck mounted between said conical seats to be actuated thereby for `grippingfand releasing, respectively., of a tool shank, a cap at the forward end of said 'casing and Yadapted to be screwed forwards and backwards relative thereto, said cap surrounding the forward end of said spindle, ian axial thrust bearing having one race mounted in `said front cap and rhaving .another race operatively "connected with said axially displace'able chuck-'actuating member for controlling axial displacement there of towards and awa-y from vsaid tool-gripping chuck in accordance with vaxial ydisplaceirren't or said cap.

i3. A Vhandpiece for Arotary tools, comprising 'a tubular casing, `a lspindle mounted for rotation in said casing by means of bearings adapted `vto receive axial and radial thr-ust, lan axial recess in the forward end ci said spindle, said recess being restricted at its outer end `to constitute la conical seat facing the inner end of said recess, an axially slidable chuck-actuating member in said recess having another conical seat Afacing said first-named seat and yprovided 'with radial projections extending through longitudinal `slots in the wallssurrounding said recess, a tool-:gripping chuck mounted vbetween said opposed seats, resilient means interposed vbetween the inner end of said recess and said chuck-actuating member for .urging the 'latter to engage said tool-gripping chuck `between said seats Vfor causing it to grip a tool-shank introduced'thereima front cap on said casing and surrounding said forward end vof said spindle, vsaid cap .being adapted to be axially adjusted relative to said casing and said spindle, an

axial thrust bearing in said cap, and a socket enclosed in said cap and surrounding said forward end of said spindle and having one end supported by said last-named bearing and being adapted to engage said radial projections to disengage said axially slidable chuck actuating member from said tool gripping chuck against the action of said resilient means according to axial adjustment of said front cap.

4. A handpiece for rotary tools, comprising a substantially tubular casing, a cap at the forward end of said casing adapted to be axially adjusted relative thereto, a bearing in said casing and another bearing in said front cap, said bearings being mounted co-axially and being of a type capable of receiving radial as well as axial thrust, a rotatable spindle mounted with its rear end in the bearing of said casing and having its forward end enclosed in saidvfront cap, a socket slidably surrounding said forward end of said spindle and mounted for rotation in said bearing of said front cap to be axially adjusted therewith, an axial recess in the'forward end of said spindle, said recess being restricted at its outer end to constitute an inner conical seat, an axially slidable v chuck-actuating member in said recess having another conical seat facing said first-named seat and provided with radial projections extending through longitudinal slots in the walls surrounding said recess to engage said socket for axial movement of said chuck-actuating member with said socket, a tool-gripping chuck mounted between said opposed seats, and resilient means interposed between the inner end of said recess and said chuck-actuating member for urging the ylatter to engage said tool-gripping chuck be- Number Name Date 255,020 Rehfuss Mar. 14, 1882 287,761 Gilbert Oct. 30, 1883 1,697,576 Shotton Jan. 1, 1929 

